Standards: Appendix R - The XOR Process Used In FEC Calculations
This is an explanation of how the XOR process works in Forward Error Correction in ST2110.
This is an Appendix to our series of articles on Standards.
The FEC packets are created by combining the payload in the media packets using the XOR logical operator. The XOR operator is used because applying it once reverses all the bits in the source. A second application reverses them back to the original state with no loss of data.
The FEC is created by combining media packet 1 with media packet 2 using the XOR technique. Then the result is combined with packet 3 and so on until the last media packet. That final result is used as the FEC.
At the receiving client, the FEC is combined with all the incoming media packets in the same way. If any single packet was dropped, the result will be the content of that packet. The sequence number on the media packets should be monitored to indicate if a recoverable dropout has occurred. Recovery is only possible if ALL of the FEC packets have arrived intact.
Part of a series supported by
You might also like...
Live Sports Production: Part 1 - New Sports Production Workflows
Welcome to Part 1 of ‘Live Sports Production’ - This new multi-part series uses a round table style format to explore the technology of live sports production with some of the industry’s leading system designers. It is a fascinating insight i…
Building Software Defined Infrastructure: Virtualization Vs Microservices
How virtualization and microservices differ, and workflows where virtualization and microservices would be used or avoided in terms of reliability, flexibility and security.
IP Security For Broadcasters: Part 8 - RADIUS Network Access
Maintaining controlled access is critical for any secure network, especially when working with high-value media in broadcast environments.
Standards: Part 25 - Designing Client-Side Video Players
Here we chart the historical development of client-side video players, describe the building blocks used to create them and the relevant standards.
Microphones: Part 5 - The Variable Directivity Microphone
The variable directivity microphone is very popular for studio work. What goes on inside is very clever and not widely appreciated.